1. Field of the Invention
The present invention relates to a method of fabricating a semiconductor device by mounting a semiconductor chip on a mount member such as a lead frame, and more particularly relates to a method of fabricating a semiconductor device comprising a small semiconductor chip such as a small signal transistor.
2. Description of the Related Art
In a process for fabricating a semiconductor device, a multiplicity of semiconductor chip is cut from a single semiconductor wafer, and individual semiconductor chips are moved to and mounted on a mount member such as a lead frame.
FIGS. 6(a), 6(b) and 6(c) are illustrative views to illustrate a conventional method of fabricating a semiconductor device.
A semiconductor wafer 32 is bonded to and supported at the center of an adhesive and extensible expanding tape 31. Semiconductor chips 33 are obtained by cutting the semiconductor wafer 32 in this condition (FIG. 6(a)).
The expanding tape 31 is then extended through lateral stretching. Individual semiconductor chips 33 are thus separated from one another. The distribution region 37 of the semiconductor chips 33 is then larger in size than the semiconductor wafer 32 prior to cutting. A lead frame 36, which is a mount member whereon the semiconductor chips 33 are to be mounted, is disposed alongside the expanding tape 31 (FIG. 6(b)).
The semiconductor chip 33 to be transferred is then pushed upward from below the expanding tape 31 by a pin 34 and the semiconductor chip 33 is moved upward while being attracted by an adsorption collet 35, such that the semiconductor chip 33 is separated from the expanding tape 31. The adsorption collet 35 is then moved horizontally (as indicated by the arrow C in FIG. 6) to thereby move the semiconductor chip 33 to a position above the lead frame 36. The adsorption collet 35 is then lowered to thus mount the semiconductor chip 33 in a predetermined location on the lead frame 36 (FIG. 6(c)).
The average horizontal movement distance L6 of the semiconductor chip 33 from a position on the expanding tape 31 to a position on the lead frame 36 is half or more than half the width of the expanding tape 31. The adsorption collet 35, having completed the mounting of the semiconductor chip 33 on the lead frame 36, must then move to a position above the semiconductor chip 33 which is to be mounted next, by returning substantially the same distance.
Further, in cases where small semiconductor chips 33 are cut from a large semiconductor wafer 32, the total number of semiconductor chips 33 is enormous. For example, when semiconductor chips 33 which are 0.35 mm square are cut from a 6-inch semiconductor wafer 32, the semiconductor chips 33 number approximately 140,000. Further, the average horizontal movement distance L6 of the semiconductor chip 33 increases in accordance with an increase in the size of the semiconductor wafer 32 and of the distribution region 37 of the semiconductor chip 33. Here, according to the method of fabricating a semiconductor device described above, the time required for the movement of the adsorption collet is also substantial. Consequently, the time required to fabricate the semiconductor device is long and the productivity is not necessarily favorable.